A plasma processing apparatus including an inner tube in a vacuum chamber is known as a conventional art, the inner tube preventing products from adhering to an inner wall surface of the vacuum chamber (Patent Document 1). The inner tube is generally formed in conformity with an internal shape of the vacuum chamber. For example, if the vacuum chamber has a cylindrical shape, the inner tube is also formed in a cylindrical shape. Moreover, the inner tube is replaceably installed in the vacuum chamber. Thus, in maintenance, the inner cylinder itself may be replaced, and thereby, the maintenance can be done easily. The material of the inner tube is generally ceramic, but instead may be aluminum having an anodized surface.
Patent Document 1: Japanese Patent Application Publication No. 2005-191023